When it comes to the writing of these islands' history, the summer of 2007 will presumably forever be associated with the departure from office of the great Blair, and the meteorological craziness whereby a higher power - as if enacting a forgotten Smiths lyric - chucked all that water on Yorkshire, Humberside and the heart of England.

Slightly more controversially, it may also go down as the time that an epochal change to this country's culturescape was decisively revealed, and Britain lost something precious. I spent a great deal of this week trying to sum up this change without sounding like a berk and eventually came to the conclusion that the best thing was to quote a prophetic old Who lyric, replete with some rather dodgy wordplay and strange use of the word "very". Anyway, here goes: "Landslide, rock's a-fallin'/ Fallin' down round our very heads/ We tried, but you were yawnin'/ Look again - rock is dead/ Rock is dead/ Rock is dead."

That's right: rock is dead, or it definitely might be. One or other must be true, because Glastonbury wasn't very good. The main problem, to hear some people talk, was the preponderance of those responsible for our Great Rock Crisis: people over 30, who are apparently buying most of the tickets for great musical events, taking the kids and a hamper, and thereby ruining their essential ambience. In the last few weeks, Michael Eavis has been heard fretting about the presence of "the 30- and 40-year-olds" and longing to "get the youngsters back". To paraphrase the late Cyril Connolly, perhaps there is no more sombre enemy of good rock than the pram in the crowd.

Now, I am 37, and thus well aware that holding forth about any of this will invite charges of hypocrisy, double standards and worse. Moreover, when rock's generational codes have become so hopelessly muddled that 40- and 50somethings are also allowed in, what kind of ageist Nazi would propose any kind of upper age-limit? I didn't really want to do this, I have to say - but by way of pointing to the grave danger we face, I cannot shake off the thought of turning up aged 20 to the Stone Roses' shabby-though-huge event at Spike Island to be faced not by 20,000 wide-eyed loons from my own peer group, but serried ranks of oldies who had stopped en route at Marks & Spencer's Simply Food and were now worrying about where to put their Bugaboos. So, sod it: a lot of us need to change our habits, and here's how.

As your 30s roll on, here is list of things that you should think about leaving behind. Enter Shikari (obviously), Klaxons, the Enemy, MySpace, the Reading/Leeds "Carling Weekend", Arctic Monkeys (at least in concert), anything remotely emo, New Young Pony Club and the Pigeon Detectives. Glastonbury should also be also avoided, at least until its magic is restored - and anyway, with the proviso that Zane Lowe, the increasingly irksome Lauren Laverne and Jo Whiley will periodically pop up and spoil your fun, watching it on red-button TV is actually a better laugh than you'd think.

Instead, prepare for a world of new and more dignified fun. Though it is a boutique, faux-indie festival, surrounded by the whiff of corporate contrivance (put it this way, the cabinet's resident groover Geoff Hoon apparently went this year), the just-gone Latitude festival is apparently a scream, and the Welsh folk/neo-prog bunfight Green Man is even better. Band-wise, you might want to start thinking about people of your own age, and thus realise that a new life is just beginning - a matter not just of talents as varied as the good and old Hold Steady, Rufus Wainwright and Richard Hawley, but an inevitable embrace of music that might not spark with teenage energy, but in its ploddingly wistful way, will somehow essay your advancing years. That's why I like that Cherry Ghost record, but that'll have to wait.

Anyway, there you have it: a two-point plan that cleverly emphasises what civil servants call "self-regulation", and will thereby save rock. Who's in?